Transducer mounting and rotating system for calibrating sonars in a sea well

A transducer mounting and rotating system for use in calibrating sonars in a sea well beneath a pier at the Woods Hole Oceanographic Institution is described. The transducer is attached to a plate fitted on the end of a shaft that is supported by a sleeve bearing at the lower end of a 6-m-long trussed steel tower. A rotary table for all-weather use with ordinary television antennas has been adapted for precision use, and attached to the surface end of the shaft. Rotation is controlled by software, with user-defined parameters, from a personal computer (PC) platform. The accuracy of the rotation is ±0.1 deg. Initial calibration trials of the transducer mounting and rotating system itself are described.